What is the minimum wind speed to turn the blades of a wind turbine?

Answer 1

Wind turbines are built to wind range specifications, so the answer varies.

GE and Gamesa, to name two manufacturers, have introduced wind turbines that can start in lower winds, as low as 5 miles per hour. These wind turbines have lower top end ranges and generate less energy than wind turbines designed for higher wind ranges.

Wind turbines typically cut in at 7-9 miles per hour.

Some wind turbines are designed for very low wind conditions and will start in winds of 2-4 miles per hour. These are only useful in the very lowest of winds.

Many industrial-scale wind turbines require power from the grid to start turning, typically around their face-plate generation capacity for a few minutes to overcome inertia of the blades. Compared to hours, days and often weeks of generation, this is a trivial energy requirement. It's further offset by wind farms starting up in increments. Wind farms feed energy into the very local grid. As the first wind turbine starts generating power, that power is available to other wind turbines. A wind farm will have the later starting wind turbines starting with the energy from the earlier wind turbines.

Other answer:

The latest models supposedly can start at about 5 miles per hour wind speed, but most start at around 8 miles per hour, though it is debatable whether a really useful amount of energy can be generated at these low speeds.

The turbines also need a very large electrical 'kick-start' from the National Grid to get them into action, and a large amount of power is also required to brake them when the wind speed hits around 50-55 miles per hour, which is their upper safety limit.